<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>四个方向的边框</title>
    <style>
        li{
            width: 200px;
            height: 50px;
        }
        .li1{
            border-top: 2px solid red;
        }
        .li2{
            border-right: 2px dotted green;
        }
        .li3{
            border-bottom: 2px dashed blue;
        }
        .li4{
            border-left: 2px solid purple;
        }
    </style>
</head>
<body>
    <ul>
        <li class="li1">第一个li</li>
        <li class="li2">第二个li</li>
        <li class="li3">第三个li</li>
        <li class="li4">第四个li</li>
    </ul>
</body>
</html>